Liquid composite moulding (LCM) may for example be employed in different areas of industry for producing composite parts. When producing composites the material may be made at the same time as the structure of the finished part.
For forming the finished part a rigid tool consisting of two separable rigid parts may be used. Alternatively, an open mould process may be used in which only one rigid tool part is provided, e.g. the lower part. A fabric, prepreg layup or thermoplastic material is positioned on the rigid tool part and is covered by a vacuum bag. The vacuum bag is secured to the rigid tool part and a vacuum is applied. Furthermore, resin is infused between the rigid tool part and the vacuum bag. The resin distributes through the fabric. Subsequently, the composite part is cured. For example, an open mould process is known from DE 10 2010 062 871 A1 and WO 2011/080 289 A1.
In the process described above one of the surfaces, e.g. the upper surface, of the composite part is only covered by a vacuum bag and possibly some auxiliary materials during resin infusion and during curing. It may be difficult to achieve a high reproducibility of the quality and shape of the upper surface of the composite part.